1932 atlas of federal aid highways

[NE2]

and blank backsides:
http://www.flickr.com/photos/uconnlibrariesmagic/sets/72157631613692074/

[Brandon]

Good find!

Some things I notice, just looking at Illinois:

US-6 was in the state.  It appears to use 159th Street from Indiana to Lockport along parts of what are now IL-7.  From there, south to Joliet along State Street/Collins Street (current IL-171).  Then it takes what became US-52 west to US-51.  US-6 then follows what is now IL-92 from LaMoille to IL-82 and then IL-82 south to Geneseo.  It appears to run concurrent with US-32 to Iowa.  Once in Iowa, US-6 has supplanted US-32.

US-12 uses Northwest Highway to Crystal Lake, and then follows current IL-31 north to its current route.

US-32 went between Naperville and Aurora along Aurora Avenue/New York Street (later IL-65) instead of the current route of Oswego Road (for US-34).

US-24 follows IL-9, IL-78, and IL-100 through Canton.

Michigan:

US-41 is shown as dashed heading due north from Powers to Marquette.

US-8 meets US-2 at Hermansville instead of Norway.

US-2 is shown as dashed on a strange route via Pickford between Saint Ignace and the Soo, and the stub south of US-2 to Saint Ignace is shown as US-31.

[NE2]

Dashed means not federal aid. The direct US 2 through Rudyard was probably under construction. US 41 north of Powers and US 8 east of Pembine were in the original 1926 plan but never built. http://www.wisconsinhighways.org/maps/ProposedUS-8.html has some details.

As for old Illinois routings: https://www.aaroads.com/forum/index.php?topic=5112
And whoa about US 6 across Illinois. The official Illinois maps showed the current routes as temporary US 6, but didn't show where it was planned to go.

Other old indirect routings can be seen on US 62 in the Missouri Bootheel and US 54 via Buffalo MO.

US 62 is shown along NY 384 between Buffalo and Niagara. I don't know if this was correct.

I now understand why US 6N was originally Waterford to Erie - US 19 still went via Edinboro.

US 89 is shown on a different westerly alignment between Tucson and Phoenix. I don't think this ever really happened, but it was part of the SR 93 state route extension of US 93 and now I-10 follows it.

Again the LA area is fucked up and it's unclear what if anything used the Pasadena-San Fernando road.

US 93 goes south from Caliente.

US 51 takes an unbuilt alignment into New Orleans.

US 6 is shown going beyond Provincetown to Race Point. This could be an error where they forgot to change the line width past Provincetown.